Dimension 3000

I have puchased a HDTV recently which I would like to connect it with my desktop, but there's only VGA port in my desktop. I tried used the VGA to DVI converter adapter, but it seems like doesn't work. So I would like to install the DVI add-on interface board (which have the DVI port) directly to my desktop, is there anyone know which one I should get?
P.S. My desktop is Dell Dimension 3000

The Dell Dimension 3000 is a very good, but very basic computer. It is known for reliability, but not for expandability.
You do not have an adequate power supply to be adding much, and you are limited on video graphics.
the VGA to DVI converter adapters seldome work in those Dell series from 2200, 2300, 2400, 3000, and when they do, they do not last.
Strongly consider whether you want to shorten the life of your Dimension 3000, as that is a likely result.
The money you will spend to perform reliable upgrades could better be spent on a good used system with a PCI-e slot and a power supply with better output.